<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #d1 {
            width: 100px;
            height: 100px;
            border: 1px solid red;
            /*设置外边距
            margin-left: 100px;
            margin-top: 100px;
            margin-bottom: 50px;
            margin: 50px;*/
            /*顺时针赋值*/
            margin: 10px 20px 30px 40px;
        }
        #d2 {
            width: 100px;
            height: 100px;
            border: 1px solid blue;
            /*上下相邻元素彼此添加外边距,取最大值*/
            margin-top: 100px;
        }
        span {
            border: 1px solid blue;
        }
        #s1 {
            /*行内元素上下外边距是无效的
            margin-top: 100px;*/
            margin-right: 100px;
        }
        #s2 {
            /*左右相邻元素彼此添加外边距,两者相加之和*/
            margin-left: 50px;
        }
        #big {
            width: 200px;
            height: 200px;
            background-color: cornflowerblue;
            /*解决粘连问题*/
            overflow: hidden;
        }
        #big>div {
            width: 50px;
            height: 50px;
            background-color: darkseagreen;
            margin-left: 50px;
            /*当元素的上边缘和上级元素的上边缘重叠时,给元素添加上外边距
            会出现粘连问题*/
            margin-top: 50px;
        }
        #border_div {
            width: 200px;
            height: 200px;
            border: 10px solid blue;
            /*设置圆角*/
            border-radius: 110px;
        }
    </style>
</head>
<body>
<div id="border_div"></div>

<div id="big">
    <div></div>
</div>

<span id="s1">span1</span><span id="s2">span2</span>

<div id="d1">外边距测试</div>
<div id="d2">div2</div>
</body>
</html>